Drafting instrument.



H. e. Bp N.

DRAFTII IG INSTRUMENT.

APPLICATION FILED FEB. 24, 1911.

1,014,803, 7 PaLehtedJan. 16,1912. 7

2 SHEETS-SHEET 1.

H. G. BOHN.

DRAFTING INSTRUMENT.

APPLICATION FILED FEB. 24, 19 11.

Patented J an. 16, 1912.

2 SHEETSSHEET 2.

UNITED STATES PATENT oEEroE.

HARRY GEORGE BOI-I1\T,0F NEW YORK, N. Y.

DRAFTING INSTRUMENT.

Application filed February 24, 1911.

Specification of Letters Patent.

To all whom it may concern .Be it known that I, HARRY G. BOHN, a citizen of the United States, residing in the borough of Brooklyn, county of Kings, city and State of New York, have invented certain new and useful Improvements in Draft- J ing Instruments, of which the following is a full, clear, and exact description.

My invention relates to improvements in drafting instruments, and has for its object to produce a new and improved beam compass.

It further has for its object to produce a beam compass in which'a T-square can be used as the beam for drawing circles in any location.

It further has for its object to produce a beam compass which can easily be handled by one man in the drawing of large circles.

It further has for its object to produce a beam compass part of which can be used in drawing arcs from perspective curves.

The following is a description of an embodiment of my invention, reference being had to the accompanying drawings, in which Figure 1 isa plan View of an embodiment of my invention. Fig. 2 is an end View of the pivot point attachment. Fig. 3 is a side view of the same showing the beam to which it is attached in section. Fig. 4 is an end view of the pencil-carrying attachment. Fig. 5 is a side View of the same. Fig. 6 is an end view of the intermediate supporting attachment. Fig. 7 is a side view of the same. Fig. Sis a side view of a. modification. Fig. 9 is a detail of a portion of the same showing means for adjusting the clip, Fig. 10 shows a pencil attachment used in combination with a T-square used with a perspective curve.

Referring more particularly to the drawings, 1 is a thin fiat beam horizontally dis-.

posed relatively to the plane on which the curve is to be drawn, the same being any suitable straight edge ordinarily used at a drafting table, such as a T-square.

2 is the head of the T-square.

3 is a clamp consisting of a base 4 having adjacent to one end a clip 5 in which a downwardly projecting pin or point 6 is adjust-,

ably held by a set screw 7 The pin has a recessed portion 6 whereby the set screw 7 can be loosened without permitting the pin to fall out.

8 is a downward projection adjacent to the 1 other end of the base and preferably termiinating in an anti-friction wheel 9, whose axis passes through the pin 6. The axis of the wheel 9 is preferably at right angles to the edge of the beam 1.

I 10 is a spring secured to the base at one end and'having its other end in proximity to the upper surface of the base so as to constitute a holding means that will securely hold the beam against the base. when inserted between the spring and the base. The base has a vertical face 4 which engages the edge of the straight edge. At another point of the beam 1 is a second clamp 11 having a base 12, which carries a style clip 13 for a drawing instrument or style, such as a pencil or drawing pen. This clip has its axis inclined to the upper surface of the base so that its angle is that at which a pencil is normally held when in use. From the base extends a projection 14 preferably terminating in an anti-friction roller 14 whose axis is parallel to the edge of-the beam 1. The roller has a central groove 15 so that the bearing surfaces thereof are displaced longitudinally from the style clip,

with the result that the line made by the pencil or pen is not touched by the projection. In this way, where ink is used the line can, when desired, be gone over a second time while the ink is Wet without danger of rubbing it. To the base is attached at one end a spring 16 whose other end comes close to the upper surface of the base 12 and constitutes a holding means for securing the clamps to the beam. The base has a vertical face 17 which engages the edge of the straight edge.

The outer end of the beam is supported on two points, thepencil pointjand the projection with its roller lt on the second clamp. These, with the pivot point 8 make a three-point support on which the beam and clamps will stand upright. The projection with its roller 9 on the first clamp makes a fourth point of support which makes the structure stand even more securely, the two points of support at either end being located at opposite ends of the bases by which they are carried and on opposite sides of the vertical longitudinal plane passing through the center of .gravity of the complete apparatus consisting of the combined beam and clamp or clamps. WVhen a long horizontally disposed thin beam is used, I secure to the beam an intermediate clamp 18 having a holding spring 19 and a downward projection 20 preferably terminating in an anti-friction roller 21, whose axis is parallel to the edges of the beam, thus supporting the central portion of the beam so as to prevent its bending.

Fig. 8 shows a modification of the outer clamp. In this form a thumb-screw 22 acts to hold the clamp to the beam. In connection with the thumb-screw, a lever 23 is preferably used, the same being pivoted at 24, and having a contact surface engaging the beam. In this form the style clip 25 is shown as vertical and slidingly mounted on the base, being adjustable by a screw 26 so that a fine adjustment of the drawing point can be obtained after the clamp is placed on the beam. I prefer to make the style clip adjustable instead of the pivot point clip.

In Fig. 10, a T-square is shown in combination with the outer clamp only, and in connection with a perspective curve 27. The head of the T-square is held against the perspective curve, and as it is moved along the pencil describes a curve on a larger diameter, according to the length of the square used, thus providing a simple means for describing arcs of very long radius.

Other applications I and modifications within the spirit 0 the invention and scope of the appended c' aims will be obvious to those skilled in the art.

lVhat I claim is:

1. In a drafting instrument, the combination of a beam, a clamp adjustably secured thereto, a clip and a projection carried by said clamp, a style in said clip, said style and projection both pointing downwardly and having their lower ends disposed laterally relatively to one another so as to be on opposite sides of the vertical longitudinal plane passing through the center of gravity of the apparatus.

2. In a drafting instrument, the combination of a beam, a clamp adjustably secured thereto, astyle clip and a projection carried by said clamp, a style in said clip, said style and projection both pointing downwardly and having their lower ends disposed laterally relatively'to one another so as to be on opposite sides of the vertical longitudinal plane passing through the center of gravity of the apparatus, the lower end of the style being out from beneath the beam and on one side thereof.

3. In a drafting instrument, the combination of a horizontally disposed thin fiat beam, a clamp adjustably secured thereto, a

style clip and a projection carried by said clamp, a style in said clip, said style and projection both pointing downwardly and having their lower ends disposed laterally relatively to one another so as to be on opposite sides of the vertical longitudinal plane passing through the center of gravity of the apparatus; a second clamp removably secured to said beam at a distance from said first clamp, a point and a projection carried by said clamp and extending downwardly and disposed laterally relatively to one another so as to be on opposite sides of said plane.

4C. In a drafting instrument, the combina tion of a beam, a clamp adjustably secured thereto, a style clip and a projection carried by said clamp, both pointing downwardly and disposed laterally relatively to one another so as to be on opposite sides of the vertical longitudinal plane passing through the center of gravity of the apparatus; said projection terminating in a roller whose aXis is substantially parallel to the edges of said beam, a second clamp removably secured to said beam at a distance from said first clamp, a point and a projection carried by said clamp and extending downwardly and disposed laterally relatively to one another so as to be on opposite sides of said plane, said last named projection terminating in a roller whose axis is substantially at right angles to the edges of said beam.

5. In a drafting instrument, an attachment adapted to be secured to a beam, having in combination a base having an upper surface adapted to engage the lower surface of said beam, a clip located adjacent to one end of said base, and a projection located adjacent to the other end of said base, both pointing downwardly and means for holding said base to said beam.

6. In a drafting instrument, an attachment adapted to be secured to a beam having in combination a base having an upper surface adapted to engage the lower surface of said beam, a style clip located adjacent to one end of said base and a projection located adjacent to the other end of said base, both pointing downwardly, and means for holding said base to said beam, said style clip having its axis inclined to said upper surface.

HARRY GEORGE BOHN.

Witnesses: V

IDA M. HUNZIKER, H. BROWNELL.

Copies of this patent may be obtained. for

five cents each, by addressing the Commissioner of Patents,

' Washington, .D. C. 

